A technique for the liquid phase epitaxy of SiC was first reported by R. W. Brander (2nd Intern. Conf. on SiC, State College, Pa. 1968, p. 187) (publ. 1969) and more recently by Japanese workers (A. Suzuki et al., J. Appl. Phys. 47, 4546 (1976); M. Ikeda et al., J. Appl. Phys. 50, 8217 (1979)). A crystal of hexagonal silicon carbide, (usually of the crystal symmetry of 6H SiC; a six layer structure) is dipped in a melt of silicon saturated with silicon carbide at temperatures above 1500.degree. C. (the melting point of silicon is about 1420.degree. C.). If the 6H SiC substrate is slightly colder than the rest of the liquid, a thin layer of 6H SiC may deposit epitaxially on the 6H SiC substrate. Thus, in theory an LPE technique for the preparation of silicon carbide devices, e.g., p-n junctions, exists. In practice, however, no 6H SiC devices are commercially made by this technique. This state of affairs is essentially due to the fact that good single crystal substrates of 6H SiC are not commercially available. Moreover, laboratory made crystals are usually twinned, and each 6H SiC cystal is different from all the others.
The present invention concerns a new technique that avoids the aforementioned shortcomings and results in cubic epitaxial SiC layers and devices of a type similar to that developed by Brander, supra. However, the following important differences exist: (1) the substrates are made of cubic SiC, not of hexagonal SiC, (the optical band gap of cubic SiC is 2.39 electron volts, vs 3.02 electron volts for 6H SiC - a very considerable difference) (2) the cubic SiC substrates are in the form of thin layers formed by chemical vapor deposition (CVD) on silicon substrates of different orientation, (100), (111), etc. They are not unsupported single crystals. (3) The thickness and the area of the cubic SiC layers deposited on the Si substrates can be controlled at will, (4) no grinding and polishing of the [CVD]SiC--on -Si substrates (preforms) prior to LPE is required, (5) the electrical properties (and other properties) of the Si-supported-SiC-substrates can be tailored at will, and (6) most importantly, the area of the silicon and of the cubic SiC layers formed upon them for use as substrates can be large enough to fit the needs of mass production techniques of SiC devices. PG,4